Oral fluid is now often used as a diagnostic matrix for the detection of analytes such as antibodies, antigens, hormones and pharmaceutical drugs including drugs of abuse. The main advantages of oral fluid over other biological fluids are that oral fluid is easily accessible by non-invasive means, does not require experience in collection, as is the case with blood, and can be easily collected under observation. As such, oral fluid is used in laboratory-based and point-of-care tests for the detection of drugs of abuse, viruses and bacteria like HIV and Helicobacter pylori, therapeutic drug monitoring and DNA typing. Oral fluid is now also the preferred and most convenient matrix for testing motorists driving under the influence of drugs.
It is desirable that the procedure for using oral fluid as a diagnostic matrix should involve a rapid collection phase (important for on-site testing), the collection of a sufficient volume for immediate and subsequent analysis, and the ability to extract the analyte under investigation from the oral fluid.
Usually, oral fluid is collected by placing some form of an absorbent material in the mouth followed by extraction of the oral fluid from the absorbent material, which can be made of cotton, cellulose, rayon or any other suitable material. There are several devices described in the prior art for the collection of oral fluid. For example, WO2006/064285 describes an analyte collection apparatus that can be used for collecting oral fluid, wherein an absorbent pad is releasably gripped by a set of fingers at the end of a handle. As such, this device requires that the absorbent material is robust enough to swab a subject's mouth without the risk of mechanical failure of the material during the process, and therefore that the absorbent material is of a sufficiently high density to provide this robustness. However, the higher the density of the absorbent material, the slower rate of the sample collection and the poorer the analyte recovery. The higher density of the absorbent material therefore compromises the performance of its saliva collection function. Furthermore, the device has no means of indicating that a sufficient volume of saliva has been collected.
WO2008/012566 describes a device for the collection of oral fluid wherein a cotton or rayon swab is woven onto the end of a shaft. A glaze may then be applied over the surface of the swab to prevent disintegration of the swab in use. Without the glaze the swab would be required to be of sufficiently high density to prevent disintegration. In either case, the high density of the material or the applied glaze causes a reduction in the saliva collection performance of the device.